synchronization system

Transcription

1 Status of the optical synchronization system Holger Schlarb DESY for the LbSyn team V. Arsov, M. C. Behrens, Bock, P. Gessler, M. Felber, K. Hacker, F. Loehl, F. Ludwig, K-H. Matthiesen, B. Schmidt, S. Wesch, A. Winter, J. Zemella (Deutsches Elektronen-Synchrotron) S. Schulz, L. Wissmann (Universität Hamburg) J. Szewinski (Warsaw University of Technology Institute of Electronic Systems) W. Jalmuzna (Technical University of Lodz)

2 Optical synchronization system 2 EDFL, soliton, Δt~100fs, f=216mhz additive mode locked, P > 100mW, phase noise < 10fs ( 1kHz) Laser MLO Narrow Band. MO-RF Free space distribution + EDFA Distribution Dispersion comp., Polarization contr., Collinear bal. opt. cross-corr. Optical link <5fs Optical link <5fs Optical link <5fs Other lasers End-station Direct LO-RF Two color bal. EOMs/ Direct/ Opt. cross-corr. Seeding Interferometer Laser pulse Arrival beam/laser FB DWC/Kly A & φ cavity Desired point-to-point to stability ~ 10 fs Main issue: robustness, stability and maintainability Prototype at FLASH

3 Layout of synchronization system at FLASH 3 Implementation of entire system 06/ Implementation of complete system 2008/2009 Photo-cathode Laser L2L Laser building EO, HHG and ORS L2L L2L Seed Experiment sflash RF gun ACC 1 DWC L2RF BC2 BPM BAM ISR CDR Diag. BAM ACC 23 DWC L2RF BC3 ACC 456 BPM CDR BAM THz LOLA Laser ORS BAM BAM HHG TEO SASE-Undulators ISR L2L PPlaser L2L Seed MO MLO MLO istribution Opt-Cross.. 12 FLASH 2 FLASH II BAM Beam arrival monitor L2L Laser to laser synchronization Seed Direct laser seeding DWC High precision down converter L2RF Laser to RF conversion Di Backbone: beam based stabilization of arrival time Conjunction with high precision synchronization of lasers Synchronization of all timing critical devices ( ~ 14 incl. FLASHII) Point-to-point synchronization ~ 10 fs rms (e- < 30 fs rms) Permanent operation and long term stability /availability investigation

4 Layout of synchronization system at FLASH 4 Implementation of entire system 06/ Implementation of complete system 2008/2009 Photo-cathode L2L Laser L2L Laser building EO, HHG and ORS L2L L2L Seed Experiment sflash RF gun L2RF 3.9GHz L2RF Kryo Diag. MO MLO MLO ACC 1 DWC L2RF BC2 BPM BAM Short L. istribution ISR CDR Diag. BAM Opt-Cross.. 12 FLASH 2 FLASH II ACC 23 DWC L2RF BC3 ACC 456 BPM CDR BAM THz LOLA Laser ORS BAM BAM HHG SASE-Undulators L2L TEO ISR PPlaser L2L Seed BAM Beam arrival monitor L2L Laser to laser synchronization Seed Direct laser seeding DWC High precision down converter L2RF Laser to RF conversion Di Short link to server more end-stations Synchronization of both photo injector lasers & Providing RF for 3th cavity (monitoring/source) Monitoring for 1.3GHz at Kryo hall Engineered version ~ spring 2010

5 Key experiment 5 To verify method, the mechanical and electrical designs and for software development before assembly Fiber link stabilization in accelerator environment Complete system test: MLO, one LINK and Beam Arrival Monitor Consistency check: two BAM against each other Intra-train feedback system (ACC1) partially Consistency check: BAM versus EO partially Supply to many links + infrastructure Optical lock of Ti:Sa laser to fiber laser (OCC-EO) High precision Energy Measurement (EBPM) L2RF conversion at 1.3GHz with sub 10fs long term stability Short link implementation Synchronization of photo-injector laser (OCC-NdYLF)

6 Key experiment: - BAM versus BAM 6 Photo-cathode Laser Laser building EO, HHG and ORS Experiment sflash RF gun ACC 1 BC2 ISR CDR Diag. ACC 23 BC3 ACC 456 CDR BAM THz LOLA Laser ORS BAM HHG TEO SASE-Undulators ISR PPlaser BAM Beam arrival monitor MO MLO 216MHz : 2 Opt-Cross.. Opt-Cross.. two Bunch Arrival time Monitor in drift section (~60 m distance) evaluation of integrated timing jitter (Hz-MHz) evaluation of drifts and offsets commissioning of two links with precision laser timing requirement test of arrival time FB by regulating ACC1 amplitude

7 Optical synchronization system: Link 7 Installation of two fiber links at FLASH Courtesy: F. Löhl

8 Long term behavior of link 8 Installation of two fiber links at FLASH Much smoother correction For 6 month in operation Day/night periods & spring -> summer observable Smooth operation (interruptions understood) link 1 link 2 link 1 link 2 8 days 2 month Courtesy: F. Löhl

9 Operation principle bunch arrival time monitor 9 Principle of the bunch arrival time monitor (BAM) sampling times of ADCs The timing information of the electron bunch is transferred into a laser amplitude modulation. This modulation is measured with a photo detector and sampled by a fast ADC. 4.7 ns (216 MHz) ADC1 ADC2 14.5mm 17mm 1.2mm thick Alumina disk 6.2mm New pickup design & Improved readout resolution < 10 fs Courtesy: K. Hacker Courtesy: F. Loehl See: EPAC 06, Loehl et al., p.2781

10 Arrival time correlation between two BAMs 10 uncorrelated jitter over 4300 shots: 8.4 fs (rms) Arrival time difference contains: high h frequency laser noise (~3 MHz 108 MHz) stability of two fiber links two BAMs Single bunch resolution of entire measurement chain: < 6 fs (rms) Courtesy: F. Loehl

11 Arrival time correlation between two BAMs 11 stability over 1.5 hours: 13.1 fs uncorrelated jitter 93f 9.3 fs resolution of a single BAM stability over 4.5 hours: 19.4 fs uncorrelated jitter 13.7 fs resolution of a single BAM Courtesy: F. Loehl

12 Front-end: bunch arrival time monitors 12 First prototype of bunch arrival monitor Courtesy: F. Loehl

13 Final implementation design Distribution and optical table layout 13 MLO1 Free space opt. distribution -Switching unit -Invar base plate -Vibration isolated -16 outputs Fiber link stabilization units (max 14) MLO2 Distr. With EDFA for each link -Special passive thermal stabilization a -One output for MLO lock based on Sagnac loop at t13gh 1.3GHz Courtesy: B. Beyer

14 Master laser oscillator (MLO) 14 Original design: J. Chen et. al., Opt. Lett. 32, (2007) Specification - mode-locked erbium-doped fiber laser - repetition rate of MHz - average power > 100mW - pulse duration < 100 fs (FWHM) - integrated timing jitter < 10 fs [10Hz,40MHz] - amplitude noise < [10Hz,40MHz] 1st generation MLO 2nd generation MLO 3st generation MLO

15 Distribution system mw input 5 mw out 90% incoupling eff. Courtesy: S. Schulz

16 Distribution system 16

17 Distribution system 17 Tolerance tight: Lateral shift ~ 50um maximum Lens L1-L2 only ~2um New telescope system with z-translation stage and different lenses Good incoupling achieved ~ 85-90% Drift test need to be carried out (first test was reduction at 1 coll. Of 10% observed) However, second lens system still missing (next week produced) To be proven if this concept is optimal

18 Components test: Timing jitter added by erbium-doped fiber amplifiers 18 DUT The balanced cross-correlator can be used to measure with sub-fs resolution the timing jitter added by an EDFA. Added timing jitter in femtoseconds (500 Hz 4.5 MHz) An optimized i EDFA adds less than 500 as timing jitter! TODO: careful drift investigation Courtesy: F. Loehl, J. Mueller

19 Engineered version of link (not yet tested) 19 3 Links are completely assembled Installation scheduled Feb/March 2009 Courtesy: F. Löhl

20 Piezo driver 20

21 Piezo driver 21

22 Piezo driver 22

23 Piezo driver 23 New piezo driver chassis New power supply Separation of +-150V & +-15V Fuses accessible, control LEDs

24 Optical synchronization of Lasers 24 Test set for optical synchronization of Ti:Sa Reference laser: EDFL λ = 1550 nm Δλ = 90 nm <P EDFL > = 15mW f rep,edfl = 40:5MHz τ EDFL = 110 fs (FWHM) Diagnostic Laser: Ti:sapphire λ = 800 nm Δλ =70 nm <P Ti:Sa > = 560mW (OXC 50mW) f rep,ti:sa = 81MHz = fs (FWHM) τ Ti:Sa Working principle of balanced optical cross-correlator sum frequency generation in a BBO crystal (type-i( ), ooe) application of a group delay to backreflected input pulses measurement of both SFG intensities difference highly sensitive to timing changes independent of laser amplitude changes (balanced detection) input signal for control loop Courtesy: S. Schulz, V. Arsov

25 Optical synchronization of Lasers 25 First measurement results: individual SFG signals at fixed delay Δt Using this scheme a Ti:Sa equal amplitude balanced case amplitude change direct measure for timing changes and a Cr:forsterite vector modulator scan (scan timing between laser) laser were locked with slope of 8.7 mv/fs (amplifier and ADC noise est. < 1 mv) 300as precision!!! sufficient for control loop peak distance of 280 fs Optical lock for short times established Courtesy: S. Schulz, V.Arsov See: Opt. Letter, 2003 / Vol. 28, No. 11 p. 947

26 Status of Implementation 26 Piezo driver: 6 board can be operated, remaining 9 boards need to be repaired electronic error found Motor boxes from link commissioned (16 x 3 Motors) Motor box MLO (added T-sensors, and ADCs for Temperature control) LDD drivers (32 in operation now, all cables checked) Almost all cable work done RF lock box in production (old one did not work because of 54MHz laser) Preparation of first link is ongoing (this week hopefully) BAM DBC3 next Installation of free space distribution about 1 month New BAM version construction drawing L2RF current produced (second loop) Good result on short link version

27 Final version of beam based long. FB with 3 rd harm. cavity 27 Accelerator ~Gun ACC1 3rdACC2 ACC3 ACC4 ACC7 Laser OCC Monitor front-end BAM EBPM BAM EO 1D EBPM BAM THz 1D BAM BAM THz 1D μtca μtca μtca μtca μtca μtca μtca Fast data processing and signal correction Patrick Gessler e + Regulation Fast Patrick Gessler 3GHz NRFcavity Process: a) Tuning of FEL (P, λ, Δt, t) b) Determination of correction algorithm c) Switch on FB + gain adjustments A Correction Algorithm/μTCA Slow A,φ 1.3 GHz SRF ACC1 (2&3) Simcon/μTCA A,φ Requirement Pkpk ΔE/E < 5 10 BC2 3.9 GHz SRFcavities Simcon/μTCA SRF regulation Christian Schmidt Jaroslaw Szewinski Beam based dfb on/off Adaptive feed forward A, φ, A, φ Integration piezo regulation ACC1 Transition RF-FB to BB-FB Diagnostics for FB regulation Acception handling Fast IO communication with μtca

28 28 Thanks for your attention